The setup is this. The Doctor still saddened by the departure of his granddaughter Susan lands on the Planet Dido, although at first he doesn't realize it, because he lands in a cave. Once again Barbara gets into trouble after leaving the TARDIS. I mean seriously these the Doctor's companions have the worse luck of anybody I've ever seen. One of the planet's inhabitants knock her off a cliff where she is rescued by a young teenager named Vicki. We find out she is from Earth in the future and has crash landed on the planet. Only one other person and herself survived. Well she's waiting on a rescue ship to come get them the hell out of dodge. At first she thinks Barbara is one of the rescue crew.
Very short episode with a nice twist at the end but all in all not one of my favorites. Maybe its because the actors is not really given much to do.
The Romans on the other hand was back to good quality writing and adventuring. This time they land near Rome during the time of Nero. We actually see the gang relaxing and getting some well deserved rest as they ummmm borrow a house from somebody who must be on vacation. (Beverly Hills Cop moment.)
But soon the Doctor gets restless, grabs up Vicki and sets out for the city of Rome to explore. Meanwhile we start to see a relationship really forming between Ian and Barbara. That makes what happens next all the more messed up as everybody gets separated.
Once again a very high quality episode I highly recommend.
For more information visit: http://en.wikipedia.org/wiki/The_Rescue_(Doctor_Who)